The invention relates to a heating system including a cooling circuit with a delivery unit for circulating the cooling liquid, and a heating loop connected to the cooling circuit and having a heat exchanger arranged in the passenger compartment of a motor vehicle. The feeding line of the heat exchanger is connected to the cooling circuit at a point downstream of the vehicle engine in the direction of flow of the liquid. The return line of the heat exchanger is connected to the delivery unit of the cooling circuit. A heating system is already commercially available in which, in addition to the delivery unit maintaining the cooling circulation, there is arranged in the heating loop a heating pump which, when required, when the heating system is activated, ensures the proper flow of the cooling water heated by the internal combustion engine through the heat exchanger. However, when there is no longer a need for heat, a solenoid valve arranged between the heating pump and the heat exchanger blocks the supply of heat to the heat exchanger. In this operating condition of the heating system, the heating pump operates against the closed valve, this leading to increased operating noises which, amplified by the vehicle body, acting as a sound board, can be a considerable disturbance. Furthermore, the construction of the known heating system as regards the solenoid valve is very complicated and operation is not very economical in view of the fact that the heating pump, operating against the closed valve, runs constantly when the automatic heating system is switched on.